Disclosed herein are an apparatus and a method of video pre-processing for motion estimation, the apparatus comprising a similarity description module, a storage module, a verdict module, and a motion estimation module. The similarity description module receives a first image in a video, the first image consisting of first blocks, and calculates the similarity descriptors of every first block and a second block of a second image in the video. The second block corresponds to a reference block among the first blocks. The similarity descriptor of each block, which corresponds to a pixel matrix, indicates whether the pixel values of at least one pair of adjacent pixels in the pixel matrix are identical. The verdict module determines whether the similarity descriptors of the second and reference blocks are identical and reaches a verdict, whereby motion estimation is selectively performed on the second block.